按钮代码，计算累计总产值，代码保存出错，如何修改，请各位老师指教，谢谢！！

For Each dr As DataRow In DataTables("scjyyb").DataRows
    If dr.IsNull("年月") OrElse dr.IsNull("单位") OrElse dr.IsNull("总产值") Then
        dr("累计_总产值") = Nothing
    Else
        Dim dqny As String = dr("年月")
        Dim sqny As String
        Dim nf As String  = Left(dqny,5)
        Dim yf As String = Right(dqny,2)
        If yf = 01 Then
            dr("累计_总产值")  = dr("总产值")
        Else
            If CByte(yf) < 11
                sqny = Left(dqny,5) & 0 & CStr(CByte(yf)-1)
            Else
                sqny = Left(dqny,5) & CStr(CByte(yf)-1)
            End If
            Dim dr1 As DataRow = e.DataTable.Find("单位 = \'" & dr("单位") & "\' And 年月 = \'" & sqny & "\'")
            If dr1 IsNot Nothing Then
                dr("累计_总产值") = dr1("累计_总产值") + dr("总产值")
            Else
                dr("累计_总产值")  = 0
            End If
        End If
    End If
Next

谢谢kylin老师的回复，好像还是不行，错误提示如下：

此主题相关图片如下：l.png

还请帮助想想办法。

原来代码是在表的DataColChanged事件中运行，没有问题，现在想把它放到按钮中去，不知道如何修改，附上原来的代码：

Select Case e.DataCol.Name
    Case "年月","单位","总产值"
        Dim sqny As String
        Dim dr As DataRow = e.DataRow
        If dr.IsNull("年月") OrElse dr.IsNull("单位") OrElse dr.IsNull("总产值") Then
            dr("累计_总产值") = Nothing
        Else
            Dim dqny As String = dr("年月")
            Dim nf As String  = Left(dqny,5)
            Dim yf As String = Right(dqny,2)
            If yf = 01 Then
                dr("累计_总产值")  = dr("总产值")
            Else
                If CByte(yf) < 11
                    sqny = Left(dqny,5) & 0 & CStr(CByte(yf)-1)
                Else
                    sqny = Left(dqny,5) & CStr(CByte(yf)-1)
                End If
                Dim dr1 As DataRow = e.DataTable.Find("单位 = \'" & dr("单位") & "\' And 年月 = \'" & sqny & "\'")
                If dr1 IsNot Nothing Then
                    dr("累计_总产值") = dr1("累计_总产值") + dr("总产值")
                Else
                    dr("累计_总产值")  = 0
                End If
            End If
        End If
End Select